The invention relates to improvements in endless flexible torque transmitting devices, and more particularly to improvements in so-called link chains (also known as pintle chains) which can be trained over and can transmit torque between driving and driven rotary parts, for example, over two or more adjustable pulleys or sheaves forming part of an infinitely or continuously variable transmission (CVT) in the power train of a motor vehicle.
A link chain of the above outlined character normally comprises a series of composite links each of which extends transversely of the chain and each of which can comprise a group or array of plate-like components. The components have openings for pintles which extend transversely of the chain and each of which articulately connects two successive links to each other so that the thus coupled links can pivot with respect to one another. Reference may be had, for example, to U.S. Pat. No. 5,427,583 (granted Jun. 27, 1995 to Wolf for xe2x80x9cLOW-NOISE, TRIPLE SIDE BAR SPROCKET CHAIN FOR INFINITELY VARIABLE TRANSMISSIONxe2x80x9d) and U.S. Pat. No. 4,927,404 (granted May 22, 1990 to Rattunde for xe2x80x9cLINK CHAIN FOR AN INFINITELY VARIABLE CONE DRIVE DISK TRANSMISSIONxe2x80x9d). The disclosure of each and every US and foreign patent and patent application mentioned in the specification of the present application, as well as that of the commonly owned German priority application Serial No. 199 43 010.1 (filed Sep. 9, 1999), is incorporated herein by reference.
A feature of a continuously variable transmission (CVT) is that, at least within a certain range, it can be set to furnish any one of an infinite number of different speed ratios. For example, a CVT can be set to furnish any desired speed ratio between the output element (such as a crankshaft or a camshaft) of a prime mover (such as a combustion engine) of a motor vehicle and the axles of the front and/or rear wheels. This is accomplished by training an endless flexible element (such as a link chain or pintle chain) over a pair of adjustable pulleys each having an axially fixed and an axially adjustable conical flange. The ratio is changed by moving the adjustable flange of one pulley toward the adjacent coaxial axially fixed flange and by simultaneously moving the adjustable flange of the other pulley axially of and away from the respective axially fixed flange. The means for moving the axially movable or shiftable flanges relative to the respective axially fixed flanges often comprises fluid-operated (preferably hydraulic) cylinder and piston assemblies and a control unit which actuates the two assemblies simultaneously, i.e., one of the axially movable flanges moves toward while the other axially movable flange moves away from the associated axially fixed flange, or vice versa. Since the length of the link chain is fixed, the just described simultaneous adjustments of the two axially movable flanges necessarily result in a change of the transmission ratio as well as in uninterrupted transmission of torque in the course of the actual selection of a desired speed ratio.
German patent No. 696 00 141 T2 discloses a link chain wherein each link comprises several components and wherein neighboring links are articulately connected to each other by pintles each of which comprises a pair of elongated rocker elements. This chain has gained acceptance in the relevant industry. However, the patented chain exhibits certain drawbacks such as excessive vibration in actual use. Excessive vibration entails the generation of pronounced noise and adversely affects the reliability and safety of the CVT in actual use. Furthermore, the patented chain is rather bulky which limits its usefulness or necessitates extensive redesigning of parts which embody or cooperate with such transmission.
German patent No. 38 26 809 C1 discloses a modified link chain wherein the links employ components having different thicknesses (as measured transversely of the chain) and/or consisting of different materials. The purpose of such design is to account for the fact that the load upon the links varies as seen transversely of the chain. Thus, the load is normally higher at the marginal portions as well as at the central portion but is less in the regions between the central portion and the two marginal portions. The utilization of links having components of different thicknesses and/or being made of different materials is intended to compensate for the aforementioned variations of load. A drawback of the just described chain is that it also exhibits the tendency to carry out pronounced vibratory movements when in actual use; this adversely affects the smoothness of running as well as the safety of the CVT and results in the generation of excessive noise. In addition, the components of the composite links in the patented chain undergo pronounced deformation and/or exhibit other undesirable defects after a relatively short period of actual use.
German patent No. 198 55 582 A1 discloses a link chain wherein each link comprises several components, and pintles in the form of pairs of rocker elements serving to articulately connect neighboring links to each other. The end portions of the rocker elements of each pair are connected with safety devices in the form of clamps each of which contacts at least one selected rocker element. The purpose of the safety devices is to prevent axial displacements of the rocker elements transversely of the chain, i.e., in the longitudinal directions of the respective pairs of links. The safety devices are designed with a view to ensure reliable retention of the rocker elements against axial shifting, even in the event of stretching of the link chain. It has been ascertained that, though the just described patented link chain holds the rocker elements against axial shifting transversely of the chain, this chain still exhibits several drawbacks such as pronounced vibration in actual use and the afore-discussed undesirable consequences, e.g., the generation of noise, reduced stability and/or others.
An object of the invention is to provide a novel and improved link chain or pintle chain which is constructed and assembled in such a way that it is sturdier, safer, quieter and not bulkier than heretofore known chains.
Another object of the invention is to provide a simple and inexpensive link chain which can be utilized in existing continuously variable transmissions as a superior substitute for presently known and utilized link chains.
A further object of the present invention is to provide a link chain which comprises simple and inexpensive parts and which can be assembled in a time-saving manner.
An additional object of the instant invention is to provide novel and improved links for use in the above outlined chain.
Still another object of the invention is to provide novel and improved pintles for use in the above outlined link chain.
A further object of the invention is to provide a novel and improved method of making the constituents of and of assembling links for use in a chain of the above outlined character.
Another object of the invention is to provide a continuously variable transmission employing the above outlined link chain as a means for transmitting torque between adjustable pulleys.
An additional object of the invention is to provide a power train which embodies the improved transmission and can be utilized with advantage in motor vehicles and/or for other purposes.
One feature of the invention resides in the provision of an elongated chain, such as an endless chain which can be utilized with advantage in a continuously variable transmission (CVT), e.g., in the power train of a motor vehicle. The improved chain comprises a series of successive adjacent links each of which extends transversely of the chain whereas the series extends longitudinally (lengthwise) of the chain. Each link includes a group of neighboring substantially plate-like components each having a first side and a second side. The components of each group include outer components and intermediate components, and each side of each intermediate component is adjacent a side of one of the respective neighboring components. At least one of the groups (but preferably at least two groups, for example, each group) includes a first set of components and a second set of components; in accordance with a feature of the invention, the sides of the first set of components are different from the sides of the second set of components. The improved chain further comprises elongated pintles each of which extends transversely of the chain and each of which articulately connects two adjacent links to each other.
When the chain is in actual use, e.g., in a continuously variable transmission wherein it is trained over at least two adjustable pulleys each having a fixed conical flange and an axially movable conical flange, the end faces of the pintles are or can be configurated to frictionally engage the conical surfaces of the flanges.
Each component of each group (i.e., of each link) is provided with at least one opening which extends between the first and second sides of the respective component. The openings of the components of each link are in at least partial register (overlap) with the openings of components of an adjacent link, and each pintle extends through the registering openings of the components forming part of the respective adjacent or neighboring links.
Each pintle can comprise a plurality (e.g., a pair) of elongated sections (often called rocker elements) which contact each other. Each rocker element of each pair of rocker elements is in contact with one set of components of one link and with one set of components of the other link of the respective adjacent links, i.e., of those links which are articulately connected to each other by the pintle embodying the respective rocker elements. Such chain can further comprise suitable connectors which non-rotatably secure at least one rocker element of each pintle with one of the respective (adjacent) links. The connectors in such chain can constitute form-locking connectors.
The rocker elements of each pintle or of certain pintles can be mounted in such a way that they are movable longitudinally of the respective links, i.e., transversely of the chain.
Each group of plate-like components (i.e., each link) can comprise at least one first and at least one second outer component, and such first and second outer components flank the respective intermediate components. The pintles of such chain can be installed in such a way that each of their rocker elements is movable longitudinally beyond the first as well as beyond the second outer components of the respective links (i.e., of the links which are articulately connected to each other by the respective pintle.
The rocker elements of each pintle (or of certain pintles) can be installed in such a way that they are movable relative to each other; for example, the rocker elements of one or more pintles can roll relative to and while in contact with each other. The arrangement can be such that the movements of rocker elements of one or more pintles relative to each other (while such rocker elements bear upon each other) can entail a pivoting of the respective links with reference to one another.
The at least one group of components can include the aforementioned first and second sets of components as well as at least one third component, and such third component can be provided with means for opposing or preventing movements of at least one rocker element of the respective pintle relative to at least one of the corresponding links (i.e., relative to the link which includes the at least one group of components and/or relative to one of the links which are articulately connected with such link.
Each group can include at least one first and at least one second outer component, and such first and second outer components flank the respective intermediate components. The at least one third component of at least one group of components can be arranged to oppose longitudinal movements of the aforementioned at least one rocker element from the first outer component of the respective first and second outer components in at least one angular position of the link which includes the at least one group relative to the link wich is articulately connected to the at least one group of components by the pintle embodying the at least one rocker element.
The sides of the at least one third component are or can be different from the sides of the components of the first and/or second set.
The at least one group can include one or two third components.
The intermediate components of one or more groups can include at least one component of the first set and/or at least one component of the second set; for example, each intermediate component can constitute a component of the first or second set. Alternatively, the at least one group can include at least three components of the first set and at least three components of the second set.
The aforementioned openings of the components can be configurated and dimensioned, and the rocker elements of the pintles can be mounted in the respective openings in such a way that at least one rocker element of a properly installed pintle contacts the components of the first set at a single location in the opening of each of the first set of components.
The components of the first set can be provided with means for limiting or preventing movements of the respective pintle relative to the first set of components longitudinally of the chain. For example, the openings can be elongated as seen in the longitudinal direction of the chain and the limiting means can include projections which are configurated and distributed in such a way that they oppose movements of pintles lengthwise of the respective openings. Furthermore, such projections can serve to prevent movements of rocker elements forming part of pintles away from each other. Since each opening normally receives portions of two pintles, the projections can be arranged to hold each of the two pintles in the respective opening against sidewise movement longitudinally of the opening, i.e., longitudinally of the chain.
The projections can extend directly into the openings of the respective components. Still further, the projections can be designed to hold the rocker elements of pintles in the respective openings against movement away from each other (as seen longitudinally of the chain).
It is also within the purview of the invention to provide at least one component of at least one of the sets with means for limiting movements of at least a portion of the respective link relative to at least a portion of an adjacent link. The limiting means can be designed to limit pivotal movements of adjacent (articulately connected) links relative to each other. For example, the limiting means can comprise at least one external protuberance on the at least one component of the at least one set. The at least one protuberance can extend longitudinally of the chain. Furthermore, the at least one component of the at least one set can be provided with two external protuberances; one such protuberance extends longitudinally of the chain in a first direction and the other protuberance also extends longitudinally of the chain but in a second direction counter to the first direction.
If the at least one group of components further includes a third set of components, the components of all three sets can extend lengthwise of the chain and each such set can include at least two neighboring components.
In accordance with a presently preferred embodiment, the outer components of each group (i.e., of each link) can include spaced-apart first and second subgroups or assemblies each of which is composed of at least two neighboring components, and the intermediate components of each such group can include a third assembly which is composed of at least two neighboring components identical with the components of the first and second assemblies. The intermediate components of each such group further include a fourth assembly of at least two neighboring components between the first and third assemblies and a fifth assembly of at least two neighboring components between the second and third assemblies. The first, second and third assemblies constitute the components of one of the first and second sets, and the components of the fourth and fifth assemblies constitute the components of the other of the first and second sets.
The just described presently preferred embodiment can be modified in such a way that each of the five assemblies can be replaced with a unit embodying one or more components. For example, at least one of these units can comprise at least two substantially plate-like components.
In accordance with a further modification, the outer components of the at least one group form part of one of the first and second sets of components and include first and second assemblies of at least two components each; these first and second assemblies flank the intermediate components of the at least one group.
Alternatively, the outer components of the at least one group can form part of one of the sets and the intermediate components of the at least one group include at least one component of the other set.
The intermediate components of the at least one group can include an assembly of components forming part of one of the sets and being located at least substantially midway between the first and second outer components of the at least one group.
In accordance with still another modification, the outer components of the at least one group include at least one first and at least one second outer component, and such first and second outer components flank the intermediate components of the at least one group. At least one intermediate component and the first and second outer components of the at least one group form part of one of the first and second sets of components, and the intermediate components of the at least one group further comprise at least one first component forming part of the other of the first and second sets of components and being disposed between one of the first and second outer components and the at least one intermediate component. The intermediate components further include at least one second component which is identical with the first component and is disposed between the at least one intermediate component and the other of the first and second outer components.
At least one first component of the at least one group (e.g., of each group) can consist (at least in part) of a first material, and at least one second component of the at least one group can consist (at least in part) of a second material which is different from the first material. It is also possible to make one or more components of the first set of a first material and to make one or more components of the second set, in their entirety, of a second material other than the first material.
The components of the first set can have a first length (as seen longitudinally of the chain), and the components of the second set can have a second length which is different from the first length.
Still further, the components of the first set can have a first strength (stability), and the components of the second set can have a second strength which is different from the first strength.
The components of at least one of the first and second sets can include means for guiding the pintles, and the components of the other of such sets can be constructed and assembled to at least reduce the tendency of the chain to vibrate in actual use.
The components of at least one of the sets can consist of a material which undergoes elastic and/or plastic deformation in response to longitudinal stretching of the chain. Alternatively, all components can be made of a material which permits such components to undergo elastic deformation but enables the components to resist plastic deformation during stretching of the chain in actual use, e.g., in a continuously variable transmission.
Another feature of the present invention resides in the provision of a continuously variable transmission which comprises a first adjustable rotary pulley or sheave, a second adjustable rotary pulley or sheave, and an endless chain which is trained over the pulleys and is constructed and assembled in the following way:
The chain comprises a series of successive adjacent links each of which extends transversely of the chain. The series of links extends longitudinally of the chain, and each link includes a group of neighboring substantially plate-like components each having a first side and a second side. The components of each group are distributed in such a way that each such group includes outer components and intermediate components and that each side of each intermediate component is adjacent a side of one of the respective neighboring components. At least one of the groups includes a first set of components and a second set of components, and the sides of the first set of components are different from the sides of the second set of components. The chain further comprises pintles each of which extends transversely of the chain and articulately connects two adjacent links to each other.
The novel features which are considered as characteristic of the invention are set forth in particular in appended claims. The improved chain itself, however, both as to its construction and the modes of assembling, installing and utilizing the same, together with numerous additional important and advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawings.